A method for decapsulating a package is provided. The method comprises steps of providing a package having a chip therein, wherein the chip has an active surface and a rear surface. Further, the package further comprises a heat sink, a plurality of solder bumps, a substrate, an underfill and a plurality of solder balls. The method further comprises removing the heat sink and removing the substrate together with the solder balls. A dry etching process is performed to remove a portion of the underfill. A wet etching process is performed to remove the rest portion of the underfill. A thermal process solder bump removal process is performed to melt the solder bumps and then a solder bump removal process is performed to remove the melted solder bumps from the active surface of the chip.